Turbo compressor and turbo refrigerator

ABSTRACT

A turbo compressor having an impeller and a rotary shaft connected to the impeller, the turbo compressor including: a positioning unit that positions the impeller and the rotary shaft in a direction orthogonal to an axis of the rotary shaft; and a rotation regulating unit installed at a location different from the positioning unit and regulating relative rotation between the impeller and the rotary shaft around the axis, in which the rotation regulating unit includes an impeller-side regulating unit integrally formed with the impeller and a shaft-side regulating unit integrally formed with the rotary shaft and locked to the impeller-side regulating unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a turbo compressor and a turbo refrigerator.

Priority is claimed on Japanese Patent Application No. 2010-87857, filed on Apr. 6, 2010, the content of which is incorporated herein by reference.

2. Description of Related Art

A turbo refrigerator having a turbo compressor that compresses a refrigerant by the rotation of an impeller and discharges the refrigerant is known as a refrigerator that cools or freezes an object to be cooled, such as water. A rotary shaft is connected to the impeller, and a driving unit such as a motor or the like is connected to the rotary shaft directly or via a plurality of gears. The rotation driving force of the driving unit is transferred to the impeller via the rotary shaft so that the impeller is rotated. When the impeller is connected to the rotary shaft, the rotary shaft is inserted into a through-hole formed in the impeller so that the impeller is fastened and fixed by means of a fastening member installed to the rotary shaft by screwing.

Also, in order to suitably transfer the rotation driving force from the rotary shaft to the impeller, a structure that regulates the relative rotation between the impeller and the rotary shaft is installed. For example, in Japanese Unexamined Patent Application, First Publication No. 2002-349484, key grooves are respectively provided to the impeller and the rotary shaft so that the relative rotation between the impeller and the rotary shaft is regulated by using a key member that is inserted into the key grooves facing each other.

However, in the structure disclosed in Japanese Unexamined Patent Application, First Publication No. 2002-349484, the key member should be prepared separately from the impeller and the rotary shaft. For this reason, the number of parts of the turbo compressor is increased, which results in an increase in manufacturing labor and costs.

In addition, the key grooves respectively formed in the impeller and the rotary shaft are often formed by a machining process (for example, a drilling process), a so-called opening process, in a state in which the impeller is mounted to the rotary shaft. However, in this processing method, since assembly work and processing work should be performed in turns, the production process becomes complicated, which results in an increase in manufacturing labor and costs.

The invention is made in consideration of the above problems and provides a turbo compressor capable of reducing manufacturing labor and costs, and a turbo refrigerator having the same.

In order to address the above object, the invention adopts the following apparatus.

SUMMARY OF THE INVENTION

In a first aspect of the invention, there is provided a turbo compressor having an impeller and a rotary shaft connected to the impeller, the turbo compressor including a positioning unit that positions the impeller and the rotary shaft in a direction orthogonal to an axis of the rotary shaft; and a rotation regulating unit installed at a location different from the positioning unit and regulating relative rotation between the impeller and the rotary shaft around the axis, wherein the rotation regulating unit includes an impeller-side regulating unit integrally formed with the impeller and a shaft-side regulating unit integrally formed with the rotary shaft and locked to the impeller-side regulating unit.

In the turbo compressor according to a second aspect of the invention, an outer peripheral shape of a cross-section of the shaft-side regulating unit in a surface orthogonal to the axis includes a plurality of first arcs arranged around the axis and curving outward in a radial direction and second arcs inscribed to the adjacent first arcs to connect the plurality of first arcs and curving outward in a radial direction so as to have a smaller diameter than the first arcs.

In the turbo compressor according to a third aspect of the invention, the plurality of first arcs is arranged at regular intervals around the axis.

In the turbo compressor according to a fourth aspect of the invention, the impeller is fastened to the rotary shaft by a fastening member screwed to the rotary shaft, and the rotation regulating unit is installed to the impeller at a side opposite to the side fastened with the fastening member.

In the turbo compressor according to a fifth aspect of the invention, the impeller is formed so that a first end thereof has a smaller outer diameter than a second end in the direction of the axis, and the positioning unit is installed at a location closer to the first end than to the second end.

In a sixth aspect of the invention, there is provided a turbo refrigerator, which includes a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to any one of the above five aspects.

According to the aspects of the invention, since the rotation regulating unit is configured by the impeller-side regulating unit and the shaft-side regulating unit integrally formed with the impeller and the rotary shaft, respectively, it is possible to reduce the number of parts of the turbo compressor. Also, the process that manufactures the impeller and the rotary shaft having the above rotation regulating unit can be simplified. Thus, there is an effect of reducing manufacturing labor and costs of a turbo compressor and a turbo refrigerator having the same.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a schematic configuration of a turbo refrigerator according to an embodiment of the invention.

FIG. 2 is a horizontal sectional view showing a turbo compressor according to an embodiment of the invention.

FIG. 3A is a schematic view showing a connection structure between a first impeller and a rotary shaft in an embodiment of the invention.

FIG. 3B is a schematic view showing the connection structure between the first impeller and the rotary shaft in an embodiment of the invention.

FIG. 3C is a schematic view showing the connection structure between the first impeller and the rotary shaft in an embodiment of the invention.

FIG. 4 is an enlarged view showing a shaft-side regulating unit in FIG. 3B.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an embodiment of the invention will be described with reference to FIGS. 1 to 4. Also, in each figure used for the following description, the scale of each component is suitably changed so that each component has a recognizable size.

FIG. 1 is a block diagram showing a schematic configuration of a turbo refrigerator S1 in this embodiment.

In this embodiment, the turbo refrigerator Si is installed at a building, a factory, or the like to generate, for example, a coolant for air conditioning and includes a condenser 1, an economizer 2, an evaporator 3, and a turbo compressor 4, as shown in FIG. 1.

The condenser 1 is supplied with a compressed refrigerant gas X1 that is a refrigerant in a compressed gas state, and cools and liquefies the compressed refrigerant gas X1 into a refrigerant liquid X2. The condenser 1 is connected to the turbo compressor 4 via a channel R1 in which the compressed refrigerant gas X1 flows and is connected to the economizer 2 via a channel R2 in which the refrigerant liquid X2 flows, as shown in FIG. 1. Also, an expansion valve 5 that decompresses the refrigerant liquid X2 is installed to the channel R2.

The economizer 2 temporarily stores the refrigerant liquid X2 decompressed by the expansion valve 5. The economizer 2 is connected to the evaporator 3 via a channel R3 in which the refrigerant liquid X2 flows and is connected to the turbo compressor 4 via a channel R4 in which a vapor-phase component X3 of the refrigerant generated by the economizer 2 flows. Also, in the channel R3, an expansion valve 6 that further decompresses the refrigerant liquid X2 is installed. In addition, the channel R4 is connected to the turbo compressor 4 so as to supply the vapor-phase component X3 to a second compression stage 22, explained later, of the turbo compressor 4.

The evaporator 3 evaporates the refrigerant liquid X2 to take evaporation heat from an object to be cooled such as water and thus cool the object to be cooled. The evaporator 3 is connected to the turbo compressor 4 via a channel R5 in which a refrigerant gas X4 generated by evaporating the refrigerant liquid X2 flows. Also, the channel R5 is connected to a first compression stage 21, explained later, of the turbo compressor 4.

The turbo compressor 4 compresses the refrigerant gas X4 into the compressed refrigerant gas X1. The turbo compressor 4 is connected to the condenser 1 via the channel R1 in which the compressed refrigerant gas X1 flows as described above and is connected to the evaporator 3 via the channel R5 in which the refrigerant gas X4 flows.

In the turbo refrigerator Si configured as above, the compressed refrigerant gas X1 supplied to the condenser 1 via the channel R1 is liquefied and cooled by the condenser 1 into the refrigerant liquid X2. The refrigerant liquid X2 is decompressed by the expansion valve 5 while being supplied to the economizer 2 via the channel R2, and is temporarily stored in the economizer 2 in a decompressed state. After that, the refrigerant liquid X2 is further decompressed by the expansion valve 6 when being supplied to the evaporator 3 via the channel R3, and is supplied to the evaporator 3 in a further decompressed state. The refrigerant liquid X2 supplied to the evaporator 3 is evaporated by the evaporator 3 to become the refrigerant gas X4 and is then supplied to the turbo compressor 4 via the channel R5. The refrigerant gas X4 supplied to the turbo compressor 4 is compressed by the turbo compressor 4 to become the compressed refrigerant gas X1 and is supplied to the condenser 1 again via the channel R1.

In addition, the vapor-phase component X3 of the refrigerant, which is generated when the refrigerant liquid X2 is stored in the economizer 2, is supplied to the turbo compressor 4 via the channel R4 to be compressed together with the refrigerant gas X4 and is supplied to the condenser 1 via the channel Ri as the compressed refrigerant gas X1.

Also, in the turbo refrigerator S1, when the refrigerant liquid X2 is evaporated in the evaporator 3, an object to be cooled is cooled or frozen by taking evaporation heat from the object to be cooled.

Subsequently, the turbo compressor 4 which has a characterizing part of this embodiment will be described in more detail. FIG. 2 is a horizontal sectional view showing the turbo compressor 4 of this embodiment.

As shown in FIG. 2, the turbo compressor 4 of this embodiment includes a motor unit 10, a compressor unit 20, and a gear unit 30.

The motor unit 10 includes a motor 12 having an output shaft 11 and serving as a driving source that drives the compressor unit 20, and a motor casing 13 that surrounds the motor 12 and to which the motor 12 is installed. Also, the driving source that drives the compressor unit 20 is not limited to the motor 12, and an internal combustion engine may be used.

The output shaft 11 of the motor 12 is rotatably supported by a first bearing 14 and a second bearing 15 fixed to the motor casing 13.

The compressor unit 20 includes a first compression stage 21 that suctions and compresses the refrigerant gas X4 (see FIG. 1) and a second compression stage 22 that further compresses the refrigerant gas X4 compressed by the first compression stage 21 and outputs it as the compressed refrigerant gas X1 (see FIG. 1).

The first compression stage 21 includes a first impeller 23 (impeller) that gives velocity energy to the refrigerant gas X4 supplied from the thrust direction to discharge the refrigerant gas X4 in a radial direction, a first diffuser 21 a that converts the velocity energy given to the refrigerant gas X4 by the first impeller 23 into pressure energy to compress the refrigerant gas X4, a first scroll chamber 21 b that guides the refrigerant gas X4 compressed by the first diffuser 21 a to an outer portion of the first compression stage 21, and an inlet port 21 c that suctions the refrigerant gas X4 and supplies the refrigerant gas X4 to the first impeller 23.

Also, the first diffuser 21 a, the first scroll chamber 21 b, and the inlet port 21 c are formed by a first impeller casing 21 d that surrounds the first impeller 23.

In the compressor unit 20, a rotary shaft 24 extending from the first compression stage 21 to the second compression stage 22 is installed. The first impeller 23 is connected to the rotary shaft 24 and is rotated by transferring a rotating power of the motor 12 to the rotary shaft 24. Also, the connection structure between the first impeller 23 and the rotary shaft 24 will be described later in detail.

In addition, a plurality of inlet guide vanes 21 e that controls a suction amount of the first compressor stage 21 is installed in the inlet port 21 c of the first compression stage 21. Each inlet guide vane 21 e is rotatable so that the area thereof that is apparent from the flowing direction of the refrigerant gas X4 may be changed by a driving mechanism 21 f fixed to the first impeller casing 21 d. Also, at the outer portion of the first impeller casing 21 d, a vane driving unit 25 connected to the driving mechanism 21 f and rotating each inlet guide vane 21 e is installed.

The second compression stage 22 includes a second impeller 26 that gives velocity energy to the refrigerant gas X4, which is compressed at the first compressor stage 21 and then supplied from the thrust direction, to discharge the refrigerant gas X4 in a radial direction, a second diffuser 22 a that converts the velocity energy given to the refrigerant gas X4 by the second impeller 26 into pressure energy to compress and discharge the refrigerant gas X4 as the compressed refrigerant gas X1 , a second scroll chamber 22 b that guides the compressed refrigerant gas X1 discharged from the second diffuser 22 a to an outer portion of the second compression stage 22, and an introducing scroll chamber 22 c that guides the refrigerant gas X4 compressed at the first compression stage 21 to the second impeller 26.

In addition, the second diffuser 22 a, the second scroll chamber 22 b, and the introducing scroll chamber 22 c are formed by a second impeller casing 22 d that surrounds the second impeller 26.

The second impeller 26 is fixed to the rotary shaft 24, explained above, so that the rear surface of the second impeller 26 faces the rear surface of the first impeller 23, and is rotated by transferring a rotating power of the motor 12 to the rotary shaft 24. In the second impeller 26, a through-hole is formed so as to pass through in a rotary shaft direction thereof, and the rotary shaft 24 is inserted into the through-hole. Also, the second impeller 26 is fixed to the rotary shaft 24 by shrink fitting or pressing-in.

The second scroll chamber 22 b is connected to the channel R1 (see FIG. 1) that supplies the compressed refrigerant gas X1 to the condenser 1 (see FIG. 1) so that the compressed refrigerant gas X1 discharged from the second compression stage 22 is supplied to the channel R1.

In addition, the first scroll chamber 21 b of the first compression stage 21 and the introducing scroll chamber 22 c of the second compression stage 22 are connected via an external pipe (not shown) installed separately from the first compression stage 21 and the second compression stage 22 so that the refrigerant gas X4 compressed at the first compression stage 21 is supplied to the second compression stage 22 via the external pipe. The channel R4 (see FIG. 1) described above is connected to the external pipe so that the vapor-phase component X3 of the refrigerant generated at the economizer 2 is supplied to the second compression stage 22 via the external pipe.

The rotary shaft 24 is rotatably supported by a third bearing 27 fixed to the second impeller casing 22 d in a space 20 a between the first compression stage 21 and the second compression stage 22 and a fourth bearing 28 fixed to the end of the second impeller casing 22 d on the side of the gear unit 30.

The gear unit 30 transfers the rotating power of the motor 12 to the rotary shaft 24 and includes a flat gear 31 fixed to the output shaft 11, a pinion gear 32 fixed to the rotary shaft 24 and engaged with the flat gear 31, and a gear casing 33 that encloses the flat gear 31 and the pinion gear 32.

The flat gear 31 has a greater outer diameter than the pinion gear 32. For this reason, the number of rotations of the rotary shaft 24 with respect to the number of rotations of the output shaft 11 is increased by engaging the flat gear 31 and the pinion gear 32 together, and then the rotating power of the motor 12 is transferred to the rotary shaft 24. Also, the force transferring method is not limited to the above, and it is also possible to set a plurality of gear diameters so that the number of rotations of the rotary shaft 24 becomes equal to or smaller than the number of rotations of the output shaft 11.

The gear casing 33 is formed separately from the motor casing 13 and the second impeller casing 22 d and connects the second impeller casing 22 d to the motor casing 13. In the gear casing 33, a receiving space 33 a that encloses the flat gear 31 and the pinion gear 32 is formed.

Also, in the gear casing 33, an oil tank 34 that collects and stores a lubricant supplied to a sliding portion of the turbo compressor 4 is installed.

Subsequently, the connection structure between the first impeller 23 and the rotary shaft 24, which is a characterizing part of this embodiment, will be described in more detail. FIGS. 3A to 3C are schematic views showing the connection structure between the first impeller 23 and the rotary shaft 24 in this embodiment, where FIG. 3A is a horizontal sectional view, FIG. 3B is a sectional view taken along the line A-A of FIG. 3A, and FIG. 3C is a sectional view taken along the line B-B of FIG. 3A. Also, in FIG. 3A, the central axis of the rotary shaft 24 is represented as an axis L.

As shown in FIG. 3A, the first impeller 23 includes a hub 23 a having a substantially conical shape and a plurality of wings 23 b (each wing is not shown) arranged in line in a circumferential direction on the outer peripheral surface of the hub 23 a. Also, since the hub 23 a is formed with a substantial conical shape, the first impeller 23 is formed so that a second end portion 23 d has a smaller outer diameter than the outer diameter of a first end portion 23 c.

Also, the hub 23 a has a through-hole 23 e penetrating in the direction of the axis L.

The rotary shaft 24 includes a first shaft portion 24 a and a second shaft portion 24 b having a smaller diameter than the first shaft portion 24 a. The second shaft portion 24 b is inserted into and installed in the through-hole 23 e of the hub 23 a.

A male screw portion 24 c is formed at the end of the second shaft portion 24 b, and a nut 29 (a fastening member) is screwed to the male screw portion 24 c. By screwing and securely fastening the nut 29 to the male screw portion 24 c, the hub 23 a is held by an end surface of the first shaft portion 24 a and the nut 29 and is fastened to the rotary shaft 24. In other words, the first impeller 23 is fastened and fixed to the rotary shaft 24 by screwing the nut 29.

At a connection point of the hub 23 a and the second shaft portion 24 b, a positioning unit C1 and a rotation regulating unit C2 located at a different position from the positioning unit C1 are installed.

The positioning unit C1 is a structure that positions the rotary shaft 24 and the first impeller 23 in a direction orthogonal to the axis L, and the positioning unit C1 is installed at a location closer to the first end portion 23 c than to the second end portion 23 d. The positioning unit C1 has an impeller-side positioning unit 23 f installed at the hub 23 a and a shaft-side positioning unit 24 d installed at the second shaft portion 24 b.

The impeller-side positioning unit 23 f is a part of the through-hole 23 e and has a circular sectional shape in a surface orthogonal to the axis L. Also, the inner diameter of the through-hole 23 e at the side of the second end portion 23 d from the impeller-side positioning unit 23 f is identical to the inner diameter of the impeller-side positioning unit 23 f.

The shaft-side positioning unit 24 d is formed with a cylindrical shape and the outer diameter thereof is sized to be press-fitted closely to the impeller-side positioning unit 23 f. By press-fitting the shaft-side positioning unit 24 d closely to the impeller-side positioning unit 23 f, it is possible to position the rotary shaft 24 to the first impeller 23 in a direction orthogonal to the axis L. Also, the diameter of the second shaft portion 24 b between the shaft-side positioning unit 24 d and the male screw portion 24 c is smaller than the shaft-side positioning unit 24 d.

Since the first impeller 23 is formed so that the second end portion 23 d has a smaller outer diameter than that of the first end portion 23 c as described above, the gravity center of the first impeller 23 is located closer to the first end portion 23 c than to the second end portion 23 d. Also, since the positioning unit Cl is also installed at a position closer to the first end portion 23 c than to the second end portion 23 d, the rotary shaft 24 can support the first impeller 23 at the gravity center thereof, and thus it is possible to stably support the first impeller 23 that is rotating.

The rotation regulating unit C2 is configured to regulate the relative rotation between the first impeller 23 and the rotary shaft 24 around the axis L and is installed at the side (or, at the side of the first end portion 23 c) of the first impeller 23 opposite to the side fastened by the nut 29. The rotation regulating unit C2 includes an impeller-side regulating unit 23 g integrally installed to the hub 23 a and a shaft-side regulating unit 24 e integrally installed to the second shaft portion 24 b.

The impeller-side regulating unit 23 g is a part of the through-hole 23 e and has a substantially triangular sectional shape in a surface orthogonal to the axis L. Also, the width of the impeller-side regulating unit 23 g in the direction orthogonal to the axis L becomes greater than the inner diameter of the impeller-side positioning unit 23 f.

The shaft-side regulating unit 24 e has a substantially triangular sectional shape in a surface orthogonal to the axis L so as to be press-fitted into the impeller-side regulating unit 23 g with a predetermined gap (not shown).

In addition, the sectional shapes of the impeller-side regulating unit 23 g and the shaft-side regulating unit 24 e are similar to each other. For this reason, the shaft-side regulating unit 24 e is press-fitted into the impeller-side regulating unit 23 g so that the shaft-side regulating unit 24 e is locked to the impeller-side regulating unit 23 g by rotating around the axis L.

Further, the sectional shape of the shaft-side regulating unit 24 e in a surface orthogonal to the axis L will be described in more detail. FIG. 4 is an enlarged view showing the shaft-side regulating unit 24 e of FIG. 3B.

As shown in FIG. 4, in the cross-section of the shaft-side regulating unit 24 e in a surface orthogonal to the axis L, the outer periphery 24 f is shaped to have three first arcs 24 g installed around the axis L and second arcs 24 h respectively installed between adjacent first arcs 24 g.

Three first arcs 24 g are arranged at regular intervals around the axis L and are installed to curve outward in a radial direction. The second arc 24 h is inscribed in the first arcs 24 g adjacent to each other to connect the first arcs 24 g adjacent to each other and curves outward in the radial direction to have a smaller diameter than the first arc 24 g. Also, the arc length of the second arc 24 h is shorter than the arc length of the first arc 24 g.

Here, the method of producing the first impeller 23 and the rotary shaft 24 will be described.

First, the first impeller 23 is, for example, formed by precise molding so that the hub 23 a and the wing 23 b are integrated. Then, the through-hole 23 e is formed in the hub 23 a. When forming the through-hole 23 e, the impeller-side positioning unit 23 f is firstly formed by drilling, and then the impeller-side regulating unit 23 g is formed by a machining process (for example, a cutting process using an end mill). When forming the impeller-side positioning unit 23 f, a hole portion having the same inner diameter as that of the impeller-side positioning unit 23 f is formed to extend from the first end portion 23 c to the second end portion 23 d. Also, the accuracy of the inner diameter of the impeller-side positioning unit 23 f is controlled to a predetermined level. Meanwhile, the processing accuracy of the impeller-side regulating unit 23 g is not as strict as the processing accuracy of the impeller-side positioning unit 23 f. Finally, the outer end surface of the wing 23 b in a radial direction is processed and adjusted in accordance with the location of the impeller-side positioning unit 23 f to complete the production of the first impeller 23.

The rotary shaft 24 is formed using cutting by a lathe or the like. All of the first shaft portion 24 a, the shaft-side positioning unit 24 d, and the second shaft portion 24 b between the shaft-side positioning unit 24 d and the end are formed by general lathe processing. Also, since the outer periphery 24 f of the shaft-side regulating unit 24 e is formed with the first arcs 24 g and the second arcs 24 h, the shaft-side regulating unit 24 e can also be formed using lathe processing by synchronizing the number of rotations and the frequency of pushing and pulling of a cutting tool (a turning tool) at a predetermined ratio in a lathe processing machine. Also, the accuracy of the outer diameter of the shaft-side positioning unit 24 d is controlled to a predetermined level. Meanwhile, the processing accuracy of the shaft-side regulating unit 24 e is not as strict as the processing accuracy of the shaft-side positioning unit 24 d. Finally, the male screw portion 24 c is formed at the end of the second shaft portion 24 b to complete the production of the rotary shaft 24.

Thus, the impeller-side regulating unit 23 g and the shaft-side regulating unit 24 e of the rotation regulating unit C2 are integrally formed with the first impeller 23 and the rotary shaft 24, respectively. For this reason, it is possible to regulate the relative rotation between the first impeller 23 and the rotary shaft 24 without using a separate member (a key member or the like) for the regulation of rotation. Also, since the impeller-side regulating unit 23 g is integrally formed with the first impeller 23 and the shaft-side regulating unit 24 e locked to the impeller-side regulating unit 23 g is integrally formed with the rotary shaft 24, there is no need to perform a machining process (an opening process or the like) in a state where the first impeller 23 is mounted to the rotary shaft 24.

In addition, manufacturing labor and costs can be reduced since the processing accuracies of the impeller-side regulating unit 23 g and the shaft-side regulating unit 24 e are not as strict as the shaft-side positioning unit 24 d or the like and the shaft-side regulating unit 24 e can be formed by the same process as the shaft-side positioning unit 24 d or the like by means of lathe processing.

Next, the assembly of the first impeller 23 and the rotary shaft 24 will be described.

The second shaft 24 b of the rotary shaft 24 is inserted into the through-hole 23 e of the first impeller 23 from the first end portion 23 c. Since the shaft-side positioning unit 24 d is press-fitted closely into the impeller-side positioning unit 23 f, the rotary shaft 24 is positioned to the first impeller 23 in a direction orthogonal to the axis L. Then, the nut 29 is screwed and securely fastened to the male screw portion 24 c protruding from the second end portion 23 d of the first impeller 23 to fasten and fix the first impeller 23 to the rotary shaft 24.

If the rotary shaft 24 is rotated in a predetermined direction (a direction in which the motor 12 (see FIG. 2) causes rotation), the shaft-side regulating unit 24 e is locked to the impeller-side regulating unit 23 g so that the relative rotation between the first impeller 23 and the rotary shaft 24 around the axis L is regulated.

In addition, as described above, since the outer periphery 24 f in the cross-section of the shaft-side regulating unit 24 e is formed with the first arcs 24 g and the second arcs 24 h, the impeller-side regulating unit 24 g is similar to the shaft-side regulating unit 24 e. For this reason, in the peripheral surface where the sectional shape is curved in an arc shape, the impeller-side regulating unit 23 g and the shaft-side regulating unit 24 e contact each other. Thus, in each of the first impeller 23 and the rotary shaft 24, the concentration of stress caused by the regulation of rotation can be eased, and thus it is possible to decrease the possibility of damage to the first impeller 23 and the rotary shaft 24.

Also, since the first arcs 24 g of the shaft-side regulating unit 24 e are arranged at regular intervals around the axis L, it is possible to ensure good balance around the axis L in a state where the rotary shaft 24 is assembled to the first impeller 23. In other words, the location of the gravity center in a state where the rotary shaft 24 is assembled to the first impeller 23 can be positioned at the same location as the axis L or in the vicinity thereof, By ensuring good balance, it is possible to reduce labor and costs for balancing after the assembly.

However, although the rotation regulating unit C2 is installed to the first end portion 23 c in this embodiment, the rotation regulating unit C2 may also be installed to the second end portion 23 d, without being limited to the above. Also, since the rotation regulating unit C2 is installed at the first end portion 23 c in this embodiment, the diameter of the male screw portion 24 c can be set substantially identical to that of the second shaft portion 24 b of the second end portion 23 d. Accordingly, it is possible to use a larger nut 29 in comparison to the case where the rotation regulating unit C2 is provided to the second end portion 23 d, which may increase a fastening force.

In this way, the rotary shaft 24 is completely assembled to the first impeller 23.

Subsequently, operations of the turbo compressor 4 of this embodiment will be described.

First, the rotating power of the motor 12 is transferred to the rotary shaft 24 via the flat gear 31 and the pinion gear 32 so that the first impeller 23 and the second impeller 26 of the compressor unit 20 are rotated.

If the first impeller 23 is rotated, the inlet port 21 c of the first compression stage 21 comes into a negative pressure state, and thus the refrigerant gas X4 flows from the channel R5 into the first compression stage 21 via the inlet port 21 c. The refrigerant gas X4 flowing into the first compression stage 21 is introduced to the first impeller 23 in a thrust direction and is discharged in a radial direction while velocity energy is given thereto by the first impeller 23. The refrigerant gas X4 discharged from the first impeller 23 is compressed as the velocity energy is converted into pressure energy by the first diffuser 21 a. The refrigerant gas X4 discharged from the first diffuser 21 a is guided out of the first compression stage 21 via the first scroll chamber 21 b. Also, the refrigerant gas X4 guided out of the first compression stage 21 is supplied to the second compression stage 22 via an external pipe, not shown.

The refrigerant gas X4 supplied to the second compression stage 22 flows into the second impeller 26 via the introducing scroll chamber 22 c from the thrust direction and is discharged in a radial direction while velocity energy is given thereto by the second impeller 26. The refrigerant gas X4 discharged from the second impeller 26 is further compressed as the velocity energy is converted into pressure energy by the second diffuser 22 a, and then the refrigerant gas X4 is considered as the compressed refrigerant gas X1. The compressed refrigerant gas X1 discharged from the second diffuser 22 a is guided out of the second compression stage 22 via the second scroll chamber 22 b. Also, the compressed refrigerant gas X1 guided out of the second compression stage 22 is supplied to the condenser 1 via the channel R1.

Thus, this embodiment can provide the following effects.

In this embodiment, since the rotation regulating unit C2 is configured with the impeller-side regulating unit 23 g and the shaft-side regulating unit 24 e that are respectively integrally formed with the first impeller 23 and the rotary shaft 24, the number of parts of the turbo compressor 4 can be reduced. Also, the process that produces the first impeller 23 and the rotary shaft 24, provided with the rotation regulating unit C2, can be simplified. Thus, in the turbo compressor 4 and the turbo refrigerator Si having the same, manufacturing labor and costs can be advantageously reduced.

While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.

For example, although the sectional shape of the rotation regulating unit C2 in a surface orthogonal to the axis L is a substantially triangular shape in this embodiment, the sectional shape is not limited thereto but may be rectangular or any other polygonal shape. Also, the sectional shape may be an oval shape or an elongated hole shape. Even though such sectional shapes are used, the outer periphery of the cross-section is preferably formed with first arcs and second arcs different from each other, in order that the shaft-side regulating unit 24 e may be formed by lathe processing as in the above embodiment.

Also, although the first arcs 24 g are arranged at regular intervals around the axis L in this embodiment, the first arcs 24 g may be arranged at different intervals, without being limited to the above.

In addition, although the shaft-side regulating unit 24 e is formed by lathe processing, it is also possible to form the first shaft portion 24 a or the shaft-side positioning unit 24 d by lathe processing and then forming the shaft-side regulating unit 24 e by a machining process, without being limited to the above. Also, in this case, the outer peripheral shape of the cross section of the shaft-side regulating unit 24 e is not necessarily formed with a plurality of arcs but may have any shape that is locked to the impeller-side regulating unit 23 g. 

1. A turbo compressor having an impeller and a rotary shaft connected to the impeller, the turbo compressor comprising: a positioning unit that positions the impeller and the rotary shaft in a direction orthogonal to an axis of the rotary shaft; and a rotation regulating unit installed at a location different from the positioning unit and regulating relative rotation between the impeller and the rotary shaft around the axis, wherein the rotation regulating unit includes an impeller-side regulating unit integrally formed with the impeller and a shaft-side regulating unit integrally formed with the rotary shaft and locked to the impeller-side regulating unit.
 2. The turbo compressor according to claim 1, wherein an outer peripheral shape of a cross section of the shaft-side regulating unit in a surface orthogonal to the axis includes a plurality of first arcs arranged around the axis and curving outward in a radial direction and second arcs inscribed to the adjacent first arcs to connect the plurality of first arcs and curving outward in a radial direction so as to have a smaller diameter than the first arcs.
 3. The turbo compressor according to claim 2, wherein the plurality of first arcs is arranged at regular intervals around the axis.
 4. The turbo compressor according to claim 1, wherein the impeller is fastened to the rotary shaft by a fastening member screwed to the rotary shaft, and the rotation regulating unit is installed to the impeller at a side opposite to the side fastened with the fastening member.
 5. The turbo compressor according to claim 2, wherein the impeller is fastened to the rotary shaft by a fastening member screwed to the rotary shaft, and the rotation regulating unit is installed to the impeller at a side opposite to the side fastened with the fastening member.
 6. The turbo compressor according to claim 3, wherein the impeller is fastened to the rotary shaft by a fastening member screwed to the rotary shaft, and the rotation regulating unit is installed to the impeller at a side opposite to the side fastened with the fastening member.
 7. The turbo compressor according to claim 1, wherein the impeller is formed so that a first end thereof has a smaller outer diameter than a second end in the direction of the axis, and the positioning unit is installed at a location closer to the first end than to the second end.
 8. The turbo compressor according to claim 2, wherein the impeller is formed so that a first end thereof has a smaller outer diameter than a second end in the direction of the axis, and the positioning unit is installed at a location closer to the first end than to the second end.
 9. The turbo compressor according to claim 3, wherein the impeller is formed so that a first end thereof has a smaller outer diameter than a second end in the direction of the axis, and the positioning unit is installed at a location closer to the first end than to the second end.
 10. The turbo compressor according to claim 4, wherein the impeller is formed so that a first end thereof has a smaller outer diameter than a second end in the direction of the axis, and the positioning unit is installed at a location closer to the first end than to the second end.
 11. The turbo compressor according to claim 5, wherein the impeller is formed so that a first end thereof has a smaller outer diameter than a second end in the direction of the axis, and the positioning unit is installed at a location closer to the first end than to the second end.
 12. The turbo compressor according to claim 6, wherein the impeller is formed so that a first end thereof has a smaller outer diameter than a second end in the direction of the axis, and the positioning unit is installed at a location closer to the first end than to the second end.
 13. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 1. 14. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 2. 15. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 3. 16. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 4. 17. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 5. 18. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 6. 19. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 7. 20. A turbo refrigerator, comprising: a condenser that cools and liquefies a compressed refrigerant; an evaporator that evaporates the liquefied refrigerant and cools an object to be cooled by taking evaporation heat from the object to be cooled; and a compressor that compresses the refrigerant evaporated by the evaporator and supplies the refrigerant to the condenser, wherein the compressor is the turbo compressor according to claim
 8. 